The Plasma Wave Observation and Sounder Experiment (PWS) observes both natural (NPW) and stimulated (SPW) plasma waves. The frequency range of the NPW system is 20 kHz to 5.12 MHz. These CDF data consist of Electric Field intensities measured by the PWS Recevier 1 (RX1) and Receiver 2 (RX2) units.

The ASPOC instrument is a single unit consisting of an electronics box and two cylindrical ion emitter modules. The emitters produce indium ions at approximately 6 KeV, in a current of less than 50 microamps. This is done by field evaporation of indium in the apex field of a needle. In the basic feedback mode of operation, a measurement of the spacecraft potential is supplied to the instrument from either the electric field experiment (EFW) or the electron analyzer (PEACE). This information is then used to adjust the emission current to reduce the spacecraft potential to some predetermined value. By default, priority is given to the EFW data, because of the higher resolution (0.034 V vs. ~1.4 V) and the more straightforward way in which the potential is derived. A calibration mode will measure the current voltage characteristics of the spacecraft, at the beginning of the mission and occasionally later to account for changes in the photoemission properties of the surface. This measurement is carried out by sweeping the ion emission current in incremental steps over some convenient range, allowing simultaneous measurements of the spacecraft potential. The length of each step is 2 to 4 spin periods. In addition to providing an improved environment for other experiments, ASPOC will permit scientific investigations of the photoelectric characteristics of the dependence of the spacecraft potential on plasma parameters, and of spacecraft charging in different plasma environments to be carried out in the so called active mode. For more details of the Cluster mission, the spacecraft, and its instruments, see the report 'Cluster: mission, payload and supporting activities,' March 1993, ESA SP 1159, and the included article 'Active Spacecraft Potential Control: an ion emitter experiment for Cluster,' by W. Riedler et al., from which this information was obtained.

This instrument (CIS: Cluster Ion Spectrometry) is capable of obtaining full 3D ion distributions with high time resolution (in one spacecraft spin) and mass-per-charge resolution. The experiment consists of two different instruments, a Hot Ion Analyzer (HIA) and a time-of-flight Ion Composition and Distribution Function analyzer (CODIF). Extensive on-board processing is done, within its dual-processor Data Processing System (DPS). CODIF determines the distributions of the major ion species with energies from spacecraft potential to 40 KeV/charge with an angular resolution of 22.5 x 10.25 degrees and with two different sensitivities. The CODIF instrument uses electrostatic deflection to select by energy per charge, with subsequent time-of-flight analysis. The sensor primarily covers the energy range 0.02-40 KeV/charge, but with additional pre-acceleration for energies below 25 eV/charge, the range is extended to energies as low as the spacecraft potential. The HIA does not measure mass, but extends the dynamic range to the highest ion fluxes, and has angular resolution capability of 5.6 x 5.6 degrees for ion-beam and solar-wind measurements. The HIA is a symmetric quadrispherical analyzer of top-hat geometry, and uses microchannel-plate electron multipliers and position encoding by discrete anodes. A 2D distribution is obtained once per 62.5 ms, and a full 3D distribution of ions in the energy range ~5 eV/charge to 32 KeV/charge is obtained every 4 s. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Cluster Ion Spectrometry Experiment, by H. Reme et al., from which this information was obtained.

This instrument (EDI: Electron Drift Instrument) measures the drift of a weak beam of test electrons that, when emitted in certain directions, return to the spacecraft after one gyration. This drift is related to the electric field and the gradient in the magnetic field, and these quantities can, by the use of different electron energies, be determined separately. The fundamental time step to determine the new parameters and direct the beams and the detectors is 2 ms. Inter-experiment links include: magnetic field information from FGM and STAFF, a blanking pulse received from WHISPER to warn of possible interference from that active experiment, and a similar blanking pulse sent to PEACE when the EDI electron beam could interfere with the PEACE electron measurement. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Electron Drift Instrument for Cluster, by G. Paschmann et al., from which this information was obtained.

The EFW (Electric Field and Waves) instrument consists of four orthogonal spherical sensors deployed from 50 m cable booms in the spin plane of the spacecraft, plus four deployment units and a main electronics unit. Each deployment unit deploys a multiconductor cable and tip-mounted spherical sensor. Each opposing pair of cables will be symmetrically deployed to a tip-to-tip distance of approximately 100 m, except for about a week at the beginning of the mission when 70 m will be used for one boom pair (the Z-booms) and 100 m for the other pair. The potentials of the spherical sensor and nearby conductors are controlled by the microprocessor to minimize errors associated with photoelectron fluxes to and from the spheres. Output signals from the sensor preamplifiers are provided to the wave instruments for analysis of high frequency wave phenomena. There is a 1 MB burst memory and tow fast A/D conversion circuits for recording electric field wave forms for time resolutions of up to 36,000 samples/s. Data gathered in the burst memory will be played back through the telemetry stream allocated to the instrument by pre-empting a portion of the real-time data. Incoming data are continuously monitored by algorithms in the software to determine whether to trigger the burst-playback mode. A large number of sampling modes is possible, yielding four possible telemetry rates from 1.440-29.440 Kbps. This data stream is transferred via the DWP instrument. The main measured quantities will be, in various modes: (1) the instantaneous spin-plane components of the electric field vector, from 0.1-700 V/Km, with time resolution down to 0.1 ms, in four frequency ranges from DC to upper limits of 10 Hz, 180 Hz, 4 KHz, or 32 KHz; (2) the AC electric field components from 10 Hz to 8 KHz, within the dynamic range of ~3 mV/Km to 10 V/Km; (3) plasma density fluctuations within the range of 1-100/cm and in three frequency ranges from 0 Hz to upper limits of 10 Hz, 180 Hz, or 4 KHz; and, (4) density and temperature (in Langmuir sweeps) in the eV range, with a dynamic range of 1-100/cm. There is also a frequency counter covering the range 10-200 KHz. On-board calculations of least-square fits to the electric field data over one spacecraft spin period (4 s) will provide a baseline of high-quality two-dimensional electric field components that are present in the telemetry stream, except for periods when three or four sensors are in current mode. The spacecraft potential is calculated and transmitted via DWP to other instruments on board. The three components from the search coil instrument (WHISPER) are also available in EFW with a bandwidth of 4 KHz. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Spherical Probe Electric Field and Waves experiment for the Cluster Mission, by G. Gustafsson et al., from which this information was obtained.

This dataset contains spin resolution unvalidated prime parameter measurements of the magnetic field vector from the fluxgate magnetometer (FGM) instrument on the Cluster 2 Rumba spacecraft. Unvalidated FGM data might sometimes contain artefacts such as spikes (duration ~ 1 spin), or short rotations (few spins). Very occasionally the data contain many spikes over several hours. Please contact Elizabeth Lucek (e.lucek@imperial.ac.uk) for more information regarding possible artefacts in specific intervals of data. The unvalidated prime parameter Data Set does not contain the spacecraft position data or additional range and telemetry mode information that the CAA parameter data set does contain.

The primary task of this instrument (PEACE: Plasma Electrons and Currents Experiment) is to obtain the velocity moments of the distribution function of electrons as frequently and as accurately as the spacecraft telemetry will allow. Detector counts are collected in energy, polar-angle, and azimuth-angle bins to form a three-dimensional matrix. Two sensors are used: LEEA (low-energy electron analyzer) and HEEA (high-energy electron analyzer). The energy coverage is from 0.67 eV to 30 KeV in 92 levels. The first 16 levels are equally spaced linearly up to 10.7 eV; the remainder are logarithmically spaced. Both sensors can use the full range, but the HEEA will normally operate over a higher energy range than the LEEA. The LEEA specializes in coverage of the energies from 0.7-10 eV, and has a geometric factor one fifth that of the HEAA. Both sensors consist of hemispherical electrostatic analyzers of the top-hat type and a detector in the form of an annular micro-channel plate with a position-sensitive readout. Each sensor covers the range 0-180 degrees with respect to the spin axis, and they are mounted opposite each other with a view perpendicular to the spin axis, thus covering the complete angular range in a half rotation of the spacecraft. The field of view perpendicular to the fan is 2 degrees for the LEEA and 5.6 degrees for the HEEA. Energy resolution (Delta-E)/E is 0.13 for LEEA and 0.16 for HEEA. There are four sweep modes, synchronized to the spin period (4 s), to vary the azimuthal angular resolution. The spin phasing can be made coincident with that of the CIS instrument, to ensure that the electron and ion moments will be measured simultaneously. On-board processing is used to calculate the moments of the distribution with an accuracy of 1% and to select suitable parts of the complete distribution for transmission. The normal science data format is based on one spin period, and consists of core data followed by other optional distributions as can be fit into the available telemetry for that spin. The core data (moments, spacecraft potential, and pitch angle distribution) are always transmitted (if the spin is nominal). The next distribution is transmitted if, before the end of the spin, all the previous data have been sent. Thus the next spin of data will be transmitted slightly late, but all of its core data will be transmitted before the following spin of data is started on. Eventually the transmission will catch up and be able to transmit the distribution after the core again, but only after some time. This applies at all telemetry rates. The instrument can adapt automatically to six different telemetry rates: a basic 1.52 Kbps rate (CIS priority); a normal 2.52 Kbps rate; an enhanced PEACE priority rate of 3.54 Kbps; and three burst mode rates, with a maximum of 15.98 Kbps. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article PEACE: a Plasma Electron and Current Experiment, by A. D. Johnstone et al., from which this information was obtained.

The dual-sensor spectrometer RAPID (Research with Adaptive Particle Imaging Detectors) analyzes suprathermal plasma distributions in the energy range from 20-400 KeV for electrons and from 2 KeV/nucleon to 1.50 MeV/nucleon for ions. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article RAPID: The Imaging Energetic Particle Spectrometer on Cluster, by B. Wilken et al., from which this information was obtained.

The Spatio-Temporal Analysis of Magnetic Field Fluctuations (STAFF) experiment provides magnetic field power spectral density values parallel and perpendicular to the magnetic field and the electric field power spectral density values for several frequency ranges. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The STAFF (Spatio-Temporal Analysis of Field Fluctuations) Experiment for the Cluster Mission, by N. Cornilleau-Wehrlin et al., from which this information was obtained.

This dataset contains 30 s duration survey spectrogram plots from the WBD instrument on the Cluster spacecraft. The spectrograms are created by 1024 point FFTs and plotted with frequency on the vertical axis, increasing time on the horizontal, and color indicating power spectral density, in relative dB. The AC electric field data are obtained by using one of the two 88m spin plane electric field antennas of the EFW instrument as a sensor. The AC magnetic field data are obtained by using one of the two search coil magnetometers (one in the spin plane, the other along the spin axis) of the STAFF instrument as a sensor.
The WBD data are obtained in one of three filter bandwidth modes: (1) 9.5 kHz, (2) 19 kHz, or (3) 77 kHz. The minimum frequency of each of these three frequency bands can be shifted up (converted) from the default 0 kHz base frequency by 125.454, 250.908 or 501.816 kHz. The time resolution of the data shown in the plots is determined from the WBD instrument mode. The highest time resolution data are sampled at 4.6 microseconds in the time domain, 4.7 milliseconds in the frequency domain (generally the 77 kHz bandwidth mode). The lowest time resolution data are sampled at 36.5 microseconds in the time domain, 37.3 milliseconds in the frequency domain (generally the 9.5 kHz bandwidth mode).
Above the spectrogram plot are a line plot panel, followed by four status lines. The line plot panel at the top provides the gain state (0 to 75 dB, in 5 dB steps) of the instrument. The four status lines provide the following information according to the color code in the upper right corner:
Data mode - whether from DSN mode (real time telemetry), or from BM2 mode (recorded onboard in Burst Mode 2) as digitally filtered or duty cycled.
Antenna - the electric field (Ey or Ez) or the magnetic field (Bx or By) antenna used.
Resolution - the data digitization level, which can be 1 bit, 4 bit or 8 bit.
Translation - the translation from base frequency of 0 kHz.
In the lower right-hand corner are the ephemeris values applicable to the start time of the plot. At the middle right-hand side are given the date and start time of the plot as well as the spacecraft number.
The University of Iowa repository maintains two types of high time resolution spectrogram plots in GIF format: a ten minute (PT10M Display Cadence) and a 30 second time span (PT30S Display Cadence). Both types of files provide information on WBD gain and operational mode, the spectral data from one spacecraft, the start date and time and ephemeris data. Overview spectrograms are also available.
The availability of these files depends on times of DSN and Pansak Ves ground station telemetry downlinks. A list of the status of the WBD instrument on each spacecraft, the telemetry time spans, operating modes and other details are available under Science Data Availability on the University of Iowa Cluster WBD web site at http://www-pw.physics.uiowa.edu/cluster/ and through the documentation section of the Cluster Active Archive (http://caa.estec.esa.int/caa).
Details on Cluster WBD Interpretation Issues can be found at http://www-pw.physics.uiowa.edu/cluster/interpretation_issues/interpretation.html
For further details on the Cluster WBD data products see Pickett, J.S., et al., "Cluster Wideband Data Products in the Cluster Active Archive" in _The Cluster Active Archive_, 2010, Springer-Verlag, pp 169-183.

The following description applies to the Wideband Data (WBD) Plasma
Wave Receivers on all four Cluster satellites, each satellite being uniquely identified
by its number (1 through 4) or its given name (Rumba, Salsa, Samba, Tango,
respectively). High time resolution calibrated waveform data sampled in one
of 3 frequency bands in the range 0-577 kHz along one axis using either an
electric field antenna or a magnetic search coil sensor. The dataset also
includes instrument mode, data quality and the angles required to orient the
measurement with respect to the magnetic field and to the GSE coordinate
system. The AC electric field data are obtained by using one of the two 88m
spin plane electric field antennas of the EFW (Electric Fields and Waves)
instrument as a sensor. The AC magnetic field data are obtained by using
one of the two search coil magnetometers (one in the spin plane, the other
along the spin axis) of the STAFF (Spatio-Temporal Analysis of Field
Fluctuations) instrument as a sensor. The WBD data are obtained in one of
three filter bandwidth modes: (1) 9.5 kHz, (2) 19 kHz, or (3) 77 kHz. The
minimum frequency of each of these three frequency bands can be shifted
up (converted) from the default 0 kHz base frequency by 125.454, 250.908
or 501.816 kHz. The time resolution of the data shown in the plots is
determined from the WBD instrument mode. The highest time resolution
data (generally the 77 kHz bandwidth mode) are sampled at 4.6
microseconds in the time domain (~4.7 milliseconds in the frequency
domain using a standard 1024 point FFT). The lowest time resolution data
(generally the 9.5 kHz bandwidth mode) are sampled at 36.5 microseconds
in the time domain (~37.3 milliseconds in the frequency domain using a
standard 1024 point FFT). The availability of these files depends on times of
DSN and Panska Ves ground station telemetry downlinks. A list of the status
of the WBD instrument on each spacecraft, the telemetry time spans,
operating modes and other details are available under Science Data
Availability on the University of Iowa Cluster WBD web site at http://www-
pw.physics.uiowa.edu/cluster/ and through the documentation section of
the Cluster Active Archive (CAA) (http://caa.estec.esa.int/caa). Details on
Cluster WBD Interpretation Issues and Caveats can be found at http://www-
pw.physics.uiowa.edu/cluster/ by clicking on the links next to the Caution symbol
in the listing on the left side of the web site. These documents are also available
from the Documentation section of the CAA website. For further details on
the Cluster WBD data products see Pickett, J.S., et al., "Cluster Wideband
Data Products in the Cluster Active Archive" in _The Cluster Active Archive_,
2010, Springer-Verlag, pp 169-183, and the Cluster WBD User Guide
archived at the CAA website in the Documentation section. ...
CALIBRATION: ... The procedure used in computing the calibrated Electric
Field and Magnetic Field values found in this file can be obtained from the
Cluster WBD Calibration Report archived at the CAA website in the
Documentation section. Because the calibration was applied in the time
domain using simple equations the raw counts actually measured by the
WBD instrument can be obtained by using these equations and solving for
'Raw Counts', keeping in mind that this number is an Integer ranging from 0
to 255. Since DC offset is a real number, the resultant when solving for raw
counts will need to be converted to the nearest whole number. A sample
IDL routine for reverse calibrating to obtain 'Raw Counts' is provided in the
WBD Calibration Report archived at the CAA. ...
CONVERSION TO FREQUENCY DOMAIN: ... In order to convert the WBD data to the frequency
domain via an FFT, the following steps need to be carried out: 1) If Electric
Field, first divide calibrated data values by 1000 to get V/m; 2) Apply
window of preference, if any (such as Hann, etc.); 3) Divide data values by
sqrt(2) to get back to the rms domain; 4) perform FFT (see Bandwidth
variable notes for non-continuous modes and/or the WBD User Guide
archived at the CAA); 5) divide by the noise bandwidth, which is equal to
the sampling frequency divided by the FFT size (see table below for
appropriate sampling frequency); 6) multiply by the appropriate constant
for the window used, if any. These steps are more fully explained in the
WBD Calibration Report archived at the CAA....
+--------------------------+
| Bandwidth | Sample Rate |
|-----------|--------------|
| 9.5 kHz | 27.443 kHz |
| 19 kHz | 54.886 kHz |
| 77 kHz | 219.544 kHz |
+--------------------------+
COORDINATE SYSTEM USED: ... One axis measurements made in the
Antenna Coordinate System, i.e., if electric field measurement, it will either
be Ey or Ez, both of which are in the spin plane of the spacecraft, and if
magnetic field measurement, it will either be Bx, along the spin axis, or By,
in spin plane. The user of WBD data should refer to the WBD User Guide,
archived at the CAA, Section 5.4.1 and Figure 5.3 for a description of the
three orientation angles provided in these files. Since WBD measurements
are made along one axis only, these three angles provide the only means for
orienting the WBD measurements with respect to a geocentric coordinate
system and to the magnetic field direction ...

The WBD (Wide Band Data) investigation is designed to provide high-resolution frequency/time spectra of plasma waves in the Earth's magnetosphere. These data files contain information on the band width, resolution, antenna angles, offsets, magnetic and electric field information. For more details of the Cluster mission, the spacecraft, and its instruments, see the report ``Cluster: mission, payload and supporting activities,'' March 1993, ESA SP-1159, and the included article ``The Wideband Plasma Wave Investigation,'' by D. A. Gurnett et al., from which this information was obtained.

The Waves of HIgh frequency and Sounder for Probing of Electron density
by Relaxation (WHISPER) performs the measurement of the electron density
on the four satellites of the Cluster project. The two main purposes of
the WHISPER experiment are to record the natural waves and to make a
diagnostic of the electron density using the sounding technique.
The various working modes and the fourier transforms calculated on board
provide a good frequency resolution obtained in the bandwidth 2-83 kHz.
Onboard data compression by the Digital Wave Processing (DWP) intrument
allows a good dynamic and level resolution of the electric signal amplitude.

The Waves of HIgh frequency and Sounder for Probing of Electron density
by Relaxation (WHISPER) performs the measurement of the electron density
on the four satellites of the Cluster project. The two main purposes of
the WHISPER experiment are to record the natural waves and to make a
diagnostic of the electron density using the sounding technique.
The various working modes and the fourier transforms calculated on board
provide a good frequency resolution obtained in the bandwidth 2-83 kHz.
Onboard data compression by the Digital Wave Processing (DWP) intrument
allows a good dynamic and level resolution of the electric signal amplitude.

The Waves of HF and Sounder for Probing Electron Density by Relaxation (WHISPER) experiment provides measurements of the electron density via active sounding of plasma resonances and records via passive wave analysis the natural wave emissions in the high-frequency range, from 4-80 KHz. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article WHISPER, a Sounder and High-Frequency Wave Analyser Experiment, by P. M. E. Decreau et al., from which this information was obtained.

The ASPOC instrument is a single unit consisting of an electronics box and two cylindrical ion emitter modules. The emitters produce indium ions at approximately 6 KeV, in a current of less than 50 microamps. This is done by field evaporation of indium in the apex field of a needle. In the basic feedback mode of operation, a measurement of the spacecraft potential is supplied to the instrument from either the electric field experiment (EFW) or the electron analyzer (PEACE). This information is then used to adjust the emission current to reduce the spacecraft potential to some predetermined value. By default, priority is given to the EFW data, because of the higher resolution (0.034 V vs. ~1.4 V) and the more straightforward way in which the potential is derived. A calibration mode will measure the current voltage characteristics of the spacecraft, at the beginning of the mission and occasionally later to account for changes in the photoemission properties of the surface. This measurement is carried out by sweeping the ion emission current in incremental steps over some convenient range, allowing simultaneous measurements of the spacecraft potential. The length of each step is 2 to 4 spin periods. In addition to providing an improved environment for other experiments, ASPOC will permit scientific investigations of the photoelectric characteristics of the dependence of the spacecraft potential on plasma parameters, and of spacecraft charging in different plasma environments to be carried out in the so called active mode. For more details of the Cluster mission, the spacecraft, and its instruments, see the report 'Cluster: mission, payload and supporting activities,' March 1993, ESA SP 1159, and the included article 'Active Spacecraft Potential Control: an ion emitter experiment for Cluster,' by W. Riedler et al., from which this information was obtained.

This instrument never worked and there is no data. This instrument (CIS: Cluster Ion Spectrometry) on the other spacecraft is capable of obtaining full 3D ion distributions with high time resolution (in one spacecraft spin) and mass-per-charge resolution. The experiment consists of two different instruments, a Hot Ion Analyzer (HIA) and a time-of-flight Ion Composition and Distribution Function analyzer (CODIF). Extensive on-board processing is done, within its dual-processor Data Processing System (DPS). CODIF determines the distributions of the major ion species with energies from spacecraft potential to 40 KeV/charge with an angular resolution of 22.5 x 10.25 degrees and with two different sensitivities. The CODIF instrument uses electrostatic deflection to select by energy per charge, with subsequent time-of-flight analysis. The sensor primarily covers the energy range 0.02-40 KeV/charge, but with additional pre-acceleration for energies below 25 eV/charge, the range is extended to energies as low as the spacecraft potential. The HIA does not measure mass, but extends the dynamic range to the highest ion fluxes, and has angular resolution capability of 5.6 x 5.6 degrees for ion-beam and solar-wind measurements. The HIA is a symmetric quadrispherical analyzer of top-hat geometry, and uses microchannel-plate electron multipliers and position encoding by discrete anodes. A 2D distribution is obtained once per 62.5 ms, and a full 3D distribution of ions in the energy range ~5 eV/charge to 32 KeV/charge is obtained every 4 s. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Cluster Ion Spectrometry Experiment, by H. Reme et al., from which this information was obtained.

This instrument (EDI: Electron Drift Instrument) measures the drift of a weak beam of test electrons that, when emitted in certain directions, return to the spacecraft after one gyration. This drift is related to the electric field and the gradient in the magnetic field, and these quantities can, by the use of different electron energies, be determined separately. The fundamental time step to determine the new parameters and direct the beams and the detectors is 2 ms. Inter-experiment links include: magnetic field information from FGM and STAFF, a blanking pulse received from WHISPER to warn of possible interference from that active experiment, and a similar blanking pulse sent to PEACE when the EDI electron beam could interfere with the PEACE electron measurement. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Electron Drift Instrument for Cluster, by G. Paschmann et al., from which this information was obtained.

The EFW (Electric Field and Waves) instrument consists of four orthogonal spherical sensors deployed from 50 m cable booms in the spin plane of the spacecraft, plus four deployment units and a main electronics unit. Each deployment unit deploys a multiconductor cable and tip-mounted spherical sensor. Each opposing pair of cables will be symmetrically deployed to a tip-to-tip distance of approximately 100 m, except for about a week at the beginning of the mission when 70 m will be used for one boom pair (the Z-booms) and 100 m for the other pair. The potentials of the spherical sensor and nearby conductors are controlled by the microprocessor to minimize errors associated with photoelectron fluxes to and from the spheres. Output signals from the sensor preamplifiers are provided to the wave instruments for analysis of high frequency wave phenomena. There is a 1 MB burst memory and tow fast A/D conversion circuits for recording electric field wave forms for time resolutions of up to 36,000 samples/s. Data gathered in the burst memory will be played back through the telemetry stream allocated to the instrument by pre-empting a portion of the real-time data. Incoming data are continuously monitored by algorithms in the software to determine whether to trigger the burst-playback mode. A large number of sampling modes is possible, yielding four possible telemetry rates from 1.440-29.440 Kbps. This data stream is transferred via the DWP instrument. The main measured quantities will be, in various modes: (1) the instantaneous spin-plane components of the electric field vector, from 0.1-700 V/Km, with time resolution down to 0.1 ms, in four frequency ranges from DC to upper limits of 10 Hz, 180 Hz, 4 KHz, or 32 KHz; (2) the AC electric field components from 10 Hz to 8 KHz, within the dynamic range of ~3 mV/Km to 10 V/Km; (3) plasma density fluctuations within the range of 1-100/cm and in three frequency ranges from 0 Hz to upper limits of 10 Hz, 180 Hz, or 4 KHz; and, (4) density and temperature (in Langmuir sweeps) in the eV range, with a dynamic range of 1-100/cm. There is also a frequency counter covering the range 10-200 KHz. On-board calculations of least-square fits to the electric field data over one spacecraft spin period (4 s) will provide a baseline of high-quality two-dimensional electric field components that are present in the telemetry stream, except for periods when three or four sensors are in current mode. The spacecraft potential is calculated and transmitted via DWP to other instruments on board. The three components from the search coil instrument (WHISPER) are also available in EFW with a bandwidth of 4 KHz. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Spherical Probe Electric Field and Waves experiment for the Cluster Mission, by G. Gustafsson et al., from which this information was obtained.

This dataset contains spin resolution unvalidated prime parameter measurements of the magnetic field vector from the fluxgate magnetometer (FGM) instrument on the Cluster 2 Salsa spacecraft. Unvalidated FGM data might sometimes contain artefacts such as spikes (duration ~ 1 spin), or short rotations (few spins). Very occasionally the data contain many spikes over several hours. Please contact Elizabeth Lucek (e.lucek@imperial.ac.uk) for more information regarding possible artefacts in specific intervals of data. The unvalidated prime parameter Data Set does not contain the spacecraft position data or additional range and telemetry mode information that the CAA parameter data set does contain.

The primary task of this instrument (PEACE: Plasma Electrons and Currents Experiment) is to obtain the velocity moments of the distribution function of electrons as frequently and as accurately as the spacecraft telemetry will allow. Detector counts are collected in energy, polar-angle, and azimuth-angle bins to form a three-dimensional matrix. Two sensors are used: LEEA (low-energy electron analyzer) and HEEA (high-energy electron analyzer). The energy coverage is from 0.67 eV to 30 KeV in 92 levels. The first 16 levels are equally spaced linearly up to 10.7 eV; the remainder are logarithmically spaced. Both sensors can use the full range, but the HEEA will normally operate over a higher energy range than the LEEA. The LEEA specializes in coverage of the energies from 0.7-10 eV, and has a geometric factor one fifth that of the HEAA. Both sensors consist of hemispherical electrostatic analyzers of the top-hat type and a detector in the form of an annular micro-channel plate with a position-sensitive readout. Each sensor covers the range 0-180 degrees with respect to the spin axis, and they are mounted opposite each other with a view perpendicular to the spin axis, thus covering the complete angular range in a half rotation of the spacecraft. The field of view perpendicular to the fan is 2 degrees for the LEEA and 5.6 degrees for the HEEA. Energy resolution (Delta-E)/E is 0.13 for LEEA and 0.16 for HEEA. There are four sweep modes, synchronized to the spin period (4 s), to vary the azimuthal angular resolution. The spin phasing can be made coincident with that of the CIS instrument, to ensure that the electron and ion moments will be measured simultaneously. On-board processing is used to calculate the moments of the distribution with an accuracy of 1% and to select suitable parts of the complete distribution for transmission. The normal science data format is based on one spin period, and consists of core data followed by other optional distributions as can be fit into the available telemetry for that spin. The core data (moments, spacecraft potential, and pitch angle distribution) are always transmitted (if the spin is nominal). The next distribution is transmitted if, before the end of the spin, all the previous data have been sent. Thus the next spin of data will be transmitted slightly late, but all of its core data will be transmitted before the following spin of data is started on. Eventually the transmission will catch up and be able to transmit the distribution after the core again, but only after some time. This applies at all telemetry rates. The instrument can adapt automatically to six different telemetry rates: a basic 1.52 Kbps rate (CIS priority); a normal 2.52 Kbps rate; an enhanced PEACE priority rate of 3.54 Kbps; and three burst mode rates, with a maximum of 15.98 Kbps. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article PEACE: a Plasma Electron and Current Experiment, by A. D. Johnstone et al., from which this information was obtained.

The dual-sensor spectrometer RAPID (Research with Adaptive Particle Imaging Detectors) analyzes suprathermal plasma distributions in the energy range from 20-400 KeV for electrons and from 2 KeV/nucleon to 1.50 MeV/nucleon for ions. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article RAPID: The Imaging Energetic Particle Spectrometer on Cluster, by B. Wilken et al., from which this information was obtained.

The Spatio-Temporal Analysis of Magnetic Field Fluctuations (STAFF) experiment provides magnetic field power spectral density values parallel and perpendicular to the magnetic field and the electric field power spectral density values for several frequency ranges. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The STAFF (Spatio-Temporal Analysis of Field Fluctuations) Experiment for the Cluster Mission, by N. Cornilleau-Wehrlin et al., from which this information was obtained.

This dataset contains 30 s duration survey spectrogram plots from the WBD instrument on the Cluster spacecraft. The spectrograms are created by 1024 point FFTs and plotted with frequency on the vertical axis, increasing time on the horizontal, and color indicating power spectral density, in relative dB. The AC electric field data are obtained by using one of the two 88m spin plane electric field antennas of the EFW instrument as a sensor. The AC magnetic field data are obtained by using one of the two search coil magnetometers (one in the spin plane, the other along the spin axis) of the STAFF instrument as a sensor.
The WBD data are obtained in one of three filter bandwidth modes: (1) 9.5 kHz, (2) 19 kHz, or (3) 77 kHz. The minimum frequency of each of these three frequency bands can be shifted up (converted) from the default 0 kHz base frequency by 125.454, 250.908 or 501.816 kHz. The time resolution of the data shown in the plots is determined from the WBD instrument mode. The highest time resolution data are sampled at 4.6 microseconds in the time domain, 4.7 milliseconds in the frequency domain (generally the 77 kHz bandwidth mode). The lowest time resolution data are sampled at 36.5 microseconds in the time domain, 37.3 milliseconds in the frequency domain (generally the 9.5 kHz bandwidth mode).
Above the spectrogram plot are a line plot panel, followed by four status lines. The line plot panel at the top provides the gain state (0 to 75 dB, in 5 dB steps) of the instrument. The four status lines provide the following information according to the color code in the upper right corner:
Data mode - whether from DSN mode (real time telemetry), or from BM2 mode (recorded onboard in Burst Mode 2) as digitally filtered or duty cycled.
Antenna - the electric field (Ey or Ez) or the magnetic field (Bx or By) antenna used.
Resolution - the data digitization level, which can be 1 bit, 4 bit or 8 bit.
Translation - the translation from base frequency of 0 kHz.
In the lower right-hand corner are the ephemeris values applicable to the start time of the plot. At the middle right-hand side are given the date and start time of the plot as well as the spacecraft number.
The University of Iowa repository maintains two types of high time resolution spectrogram plots in GIF format: a ten minute (PT10M Display Cadence) and a 30 second time span (PT30S Display Cadence). Both types of files provide information on WBD gain and operational mode, the spectral data from one spacecraft, the start date and time and ephemeris data. Overview spectrograms are also available.
The availability of these files depends on times of DSN and Pansak Ves ground station telemetry downlinks. A list of the status of the WBD instrument on each spacecraft, the telemetry time spans, operating modes and other details are available under Science Data Availability on the University of Iowa Cluster WBD web site at http://www-pw.physics.uiowa.edu/cluster/ and through the documentation section of the Cluster Active Archive (http://caa.estec.esa.int/caa).
Details on Cluster WBD Interpretation Issues can be found at http://www-pw.physics.uiowa.edu/cluster/interpretation_issues/interpretation.html
For further details on the Cluster WBD data products see Pickett, J.S., et al., "Cluster Wideband Data Products in the Cluster Active Archive" in _The Cluster Active Archive_, 2010, Springer-Verlag, pp 169-183.

The following description applies to the Wideband Data (WBD) Plasma
Wave Receivers on all four Cluster satellites, each satellite being uniquely identified
by its number (1 through 4) or its given name (Rumba, Salsa, Samba, Tango,
respectively). High time resolution calibrated waveform data sampled in one
of 3 frequency bands in the range 0-577 kHz along one axis using either an
electric field antenna or a magnetic search coil sensor. The dataset also
includes instrument mode, data quality and the angles required to orient the
measurement with respect to the magnetic field and to the GSE coordinate
system. The AC electric field data are obtained by using one of the two 88m
spin plane electric field antennas of the EFW (Electric Fields and Waves)
instrument as a sensor. The AC magnetic field data are obtained by using
one of the two search coil magnetometers (one in the spin plane, the other
along the spin axis) of the STAFF (Spatio-Temporal Analysis of Field
Fluctuations) instrument as a sensor. The WBD data are obtained in one of
three filter bandwidth modes: (1) 9.5 kHz, (2) 19 kHz, or (3) 77 kHz. The
minimum frequency of each of these three frequency bands can be shifted
up (converted) from the default 0 kHz base frequency by 125.454, 250.908
or 501.816 kHz. The time resolution of the data shown in the plots is
determined from the WBD instrument mode. The highest time resolution
data (generally the 77 kHz bandwidth mode) are sampled at 4.6
microseconds in the time domain (~4.7 milliseconds in the frequency
domain using a standard 1024 point FFT). The lowest time resolution data
(generally the 9.5 kHz bandwidth mode) are sampled at 36.5 microseconds
in the time domain (~37.3 milliseconds in the frequency domain using a
standard 1024 point FFT). The availability of these files depends on times of
DSN and Panska Ves ground station telemetry downlinks. A list of the status
of the WBD instrument on each spacecraft, the telemetry time spans,
operating modes and other details are available under Science Data
Availability on the University of Iowa Cluster WBD web site at http://www-
pw.physics.uiowa.edu/cluster/ and through the documentation section of
the Cluster Active Archive (CAA) (http://caa.estec.esa.int/caa). Details on
Cluster WBD Interpretation Issues and Caveats can be found at http://www-
pw.physics.uiowa.edu/cluster/ by clicking on the links next to the Caution symbol
in the listing on the left side of the web site. These documents are also available
from the Documentation section of the CAA website. For further details on
the Cluster WBD data products see Pickett, J.S., et al., "Cluster Wideband
Data Products in the Cluster Active Archive" in _The Cluster Active Archive_,
2010, Springer-Verlag, pp 169-183, and the Cluster WBD User Guide
archived at the CAA website in the Documentation section. ...
CALIBRATION: ... The procedure used in computing the calibrated Electric
Field and Magnetic Field values found in this file can be obtained from the
Cluster WBD Calibration Report archived at the CAA website in the
Documentation section. Because the calibration was applied in the time
domain using simple equations the raw counts actually measured by the
WBD instrument can be obtained by using these equations and solving for
'Raw Counts', keeping in mind that this number is an Integer ranging from 0
to 255. Since DC offset is a real number, the resultant when solving for raw
counts will need to be converted to the nearest whole number. A sample
IDL routine for reverse calibrating to obtain 'Raw Counts' is provided in the
WBD Calibration Report archived at the CAA. ...
CONVERSION TO FREQUENCY DOMAIN: ... In order to convert the WBD data to the frequency
domain via an FFT, the following steps need to be carried out: 1) If Electric
Field, first divide calibrated data values by 1000 to get V/m; 2) Apply
window of preference, if any (such as Hann, etc.); 3) Divide data values by
sqrt(2) to get back to the rms domain; 4) perform FFT (see Bandwidth
variable notes for non-continuous modes and/or the WBD User Guide
archived at the CAA); 5) divide by the noise bandwidth, which is equal to
the sampling frequency divided by the FFT size (see table below for
appropriate sampling frequency); 6) multiply by the appropriate constant
for the window used, if any. These steps are more fully explained in the
WBD Calibration Report archived at the CAA....
+--------------------------+
| Bandwidth | Sample Rate |
|-----------|--------------|
| 9.5 kHz | 27.443 kHz |
| 19 kHz | 54.886 kHz |
| 77 kHz | 219.544 kHz |
+--------------------------+
COORDINATE SYSTEM USED: ... One axis measurements made in the
Antenna Coordinate System, i.e., if electric field measurement, it will either
be Ey or Ez, both of which are in the spin plane of the spacecraft, and if
magnetic field measurement, it will either be Bx, along the spin axis, or By,
in spin plane. The user of WBD data should refer to the WBD User Guide,
archived at the CAA, Section 5.4.1 and Figure 5.3 for a description of the
three orientation angles provided in these files. Since WBD measurements
are made along one axis only, these three angles provide the only means for
orienting the WBD measurements with respect to a geocentric coordinate
system and to the magnetic field direction ...

The Waves of HIgh frequency and Sounder for Probing of Electron density
by Relaxation (WHISPER) performs the measurement of the electron density
on the four satellites of the Cluster project. The two main purposes of
the WHISPER experiment are to record the natural waves and to make a
diagnostic of the electron density using the sounding technique.
The various working modes and the fourier transforms calculated on board
provide a good frequency resolution obtained in the bandwidth 2-83 kHz.
Onboard data compression by the Digital Wave Processing (DWP) intrument
allows a good dynamic and level resolution of the electric signal amplitude.

The Waves of HIgh frequency and Sounder for Probing of Electron density
by Relaxation (WHISPER) performs the measurement of the electron density
on the four satellites of the Cluster project. The two main purposes of
the WHISPER experiment are to record the natural waves and to make a
diagnostic of the electron density using the sounding technique.
The various working modes and the fourier transforms calculated on board
provide a good frequency resolution obtained in the bandwidth 2-83 kHz.
Onboard data compression by the Digital Wave Processing (DWP) intrument
allows a good dynamic and level resolution of the electric signal amplitude.

The Waves of HF and Sounder for Probing Electron Density by Relaxation (WHISPER) experiment provides measurements of the electron density via active sounding of plasma resonances and records via passive wave analysis the natural wave emissions in the high-frequency range, from 4-80 KHz. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article WHISPER, a Sounder and High-Frequency Wave Analyser Experiment, by P. M. E. Decreau et al., from which this information was obtained.

The ASPOC instrument is a single unit consisting of an electronics box and two cylindrical ion emitter modules. The emitters produce indium ions at approximately 6 KeV, in a current of less than 50 microamps. This is done by field evaporation of indium in the apex field of a needle. In the basic feedback mode of operation, a measurement of the spacecraft potential is supplied to the instrument from either the electric field experiment (EFW) or the electron analyzer (PEACE). This information is then used to adjust the emission current to reduce the spacecraft potential to some predetermined value. By default, priority is given to the EFW data, because of the higher resolution (0.034 V vs. ~1.4 V) and the more straightforward way in which the potential is derived. A calibration mode will measure the current voltage characteristics of the spacecraft, at the beginning of the mission and occasionally later to account for changes in the photoemission properties of the surface. This measurement is carried out by sweeping the ion emission current in incremental steps over some convenient range, allowing simultaneous measurements of the spacecraft potential. The length of each step is 2 to 4 spin periods. In addition to providing an improved environment for other experiments, ASPOC will permit scientific investigations of the photoelectric characteristics of the dependence of the spacecraft potential on plasma parameters, and of spacecraft charging in different plasma environments to be carried out in the so called active mode. For more details of the Cluster mission, the spacecraft, and its instruments, see the report 'Cluster: mission, payload and supporting activities,' March 1993, ESA SP 1159, and the included article 'Active Spacecraft Potential Control: an ion emitter experiment for Cluster,' by W. Riedler et al., from which this information was obtained.

This instrument (CIS: Cluster Ion Spectrometry) is capable of obtaining full 3D ion distributions with high time resolution (in one spacecraft spin) and mass-per-charge resolution. The experiment consists of two different instruments, a Hot Ion Analyzer (HIA) and a time-of-flight Ion Composition and Distribution Function analyzer (CODIF). Extensive on-board processing is done, within its dual-processor Data Processing System (DPS). CODIF determines the distributions of the major ion species with energies from spacecraft potential to 40 KeV/charge with an angular resolution of 22.5 x 10.25 degrees and with two different sensitivities. The CODIF instrument uses electrostatic deflection to select by energy per charge, with subsequent time-of-flight analysis. The sensor primarily covers the energy range 0.02-40 KeV/charge, but with additional pre-acceleration for energies below 25 eV/charge, the range is extended to energies as low as the spacecraft potential. The HIA does not measure mass, but extends the dynamic range to the highest ion fluxes, and has angular resolution capability of 5.6 x 5.6 degrees for ion-beam and solar-wind measurements. The HIA is a symmetric quadrispherical analyzer of top-hat geometry, and uses microchannel-plate electron multipliers and position encoding by discrete anodes. A 2D distribution is obtained once per 62.5 ms, and a full 3D distribution of ions in the energy range ~5 eV/charge to 32 KeV/charge is obtained every 4 s. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Cluster Ion Spectrometry Experiment, by H. Reme et al., from which this information was obtained.

This instrument (EDI: Electron Drift Instrument) measures the drift of a weak beam of test electrons that, when emitted in certain directions, return to the spacecraft after one gyration. This drift is related to the electric field and the gradient in the magnetic field, and these quantities can, by the use of different electron energies, be determined separately. The fundamental time step to determine the new parameters and direct the beams and the detectors is 2 ms. Inter-experiment links include: magnetic field information from FGM and STAFF, a blanking pulse received from WHISPER to warn of possible interference from that active experiment, and a similar blanking pulse sent to PEACE when the EDI electron beam could interfere with the PEACE electron measurement. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Electron Drift Instrument for Cluster, by G. Paschmann et al., from which this information was obtained.

The EFW (Electric Field and Waves) instrument consists of four orthogonal spherical sensors deployed from 50 m cable booms in the spin plane of the spacecraft, plus four deployment units and a main electronics unit. Each deployment unit deploys a multiconductor cable and tip-mounted spherical sensor. Each opposing pair of cables will be symmetrically deployed to a tip-to-tip distance of approximately 100 m, except for about a week at the beginning of the mission when 70 m will be used for one boom pair (the Z-booms) and 100 m for the other pair. The potentials of the spherical sensor and nearby conductors are controlled by the microprocessor to minimize errors associated with photoelectron fluxes to and from the spheres. Output signals from the sensor preamplifiers are provided to the wave instruments for analysis of high frequency wave phenomena. There is a 1 MB burst memory and tow fast A/D conversion circuits for recording electric field wave forms for time resolutions of up to 36,000 samples/s. Data gathered in the burst memory will be played back through the telemetry stream allocated to the instrument by pre-empting a portion of the real-time data. Incoming data are continuously monitored by algorithms in the software to determine whether to trigger the burst-playback mode. A large number of sampling modes is possible, yielding four possible telemetry rates from 1.440-29.440 Kbps. This data stream is transferred via the DWP instrument. The main measured quantities will be, in various modes: (1) the instantaneous spin-plane components of the electric field vector, from 0.1-700 V/Km, with time resolution down to 0.1 ms, in four frequency ranges from DC to upper limits of 10 Hz, 180 Hz, 4 KHz, or 32 KHz; (2) the AC electric field components from 10 Hz to 8 KHz, within the dynamic range of ~3 mV/Km to 10 V/Km; (3) plasma density fluctuations within the range of 1-100/cm and in three frequency ranges from 0 Hz to upper limits of 10 Hz, 180 Hz, or 4 KHz; and, (4) density and temperature (in Langmuir sweeps) in the eV range, with a dynamic range of 1-100/cm. There is also a frequency counter covering the range 10-200 KHz. On-board calculations of least-square fits to the electric field data over one spacecraft spin period (4 s) will provide a baseline of high-quality two-dimensional electric field components that are present in the telemetry stream, except for periods when three or four sensors are in current mode. The spacecraft potential is calculated and transmitted via DWP to other instruments on board. The three components from the search coil instrument (WHISPER) are also available in EFW with a bandwidth of 4 KHz. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The Spherical Probe Electric Field and Waves experiment for the Cluster Mission, by G. Gustafsson et al., from which this information was obtained.

This dataset contains spin resolution unvalidated prime parameter measurements of the magnetic field vector from the fluxgate magnetometer (FGM) instrument on the Cluster 2 Samba spacecraft. Unvalidated FGM data might sometimes contain artefacts such as spikes (duration ~ 1 spin), or short rotations (few spins). Very occasionally the data contain many spikes over several hours. Please contact Elizabeth Lucek (e.lucek@imperial.ac.uk) for more information regarding possible artefacts in specific intervals of data. The unvalidated prime parameter Data Set does not contain the spacecraft position data or additional range and telemetry mode information that the CAA parameter data set does contain.

The primary task of this instrument (PEACE: Plasma Electrons and Currents Experiment) is to obtain the velocity moments of the distribution function of electrons as frequently and as accurately as the spacecraft telemetry will allow. Detector counts are collected in energy, polar-angle, and azimuth-angle bins to form a three-dimensional matrix. Two sensors are used: LEEA (low-energy electron analyzer) and HEEA (high-energy electron analyzer). The energy coverage is from 0.67 eV to 30 KeV in 92 levels. The first 16 levels are equally spaced linearly up to 10.7 eV; the remainder are logarithmically spaced. Both sensors can use the full range, but the HEEA will normally operate over a higher energy range than the LEEA. The LEEA specializes in coverage of the energies from 0.7-10 eV, and has a geometric factor one fifth that of the HEAA. Both sensors consist of hemispherical electrostatic analyzers of the top-hat type and a detector in the form of an annular micro-channel plate with a position-sensitive readout. Each sensor covers the range 0-180 degrees with respect to the spin axis, and they are mounted opposite each other with a view perpendicular to the spin axis, thus covering the complete angular range in a half rotation of the spacecraft. The field of view perpendicular to the fan is 2 degrees for the LEEA and 5.6 degrees for the HEEA. Energy resolution (Delta-E)/E is 0.13 for LEEA and 0.16 for HEEA. There are four sweep modes, synchronized to the spin period (4 s), to vary the azimuthal angular resolution. The spin phasing can be made coincident with that of the CIS instrument, to ensure that the electron and ion moments will be measured simultaneously. On-board processing is used to calculate the moments of the distribution with an accuracy of 1% and to select suitable parts of the complete distribution for transmission. The normal science data format is based on one spin period, and consists of core data followed by other optional distributions as can be fit into the available telemetry for that spin. The core data (moments, spacecraft potential, and pitch angle distribution) are always transmitted (if the spin is nominal). The next distribution is transmitted if, before the end of the spin, all the previous data have been sent. Thus the next spin of data will be transmitted slightly late, but all of its core data will be transmitted before the following spin of data is started on. Eventually the transmission will catch up and be able to transmit the distribution after the core again, but only after some time. This applies at all telemetry rates. The instrument can adapt automatically to six different telemetry rates: a basic 1.52 Kbps rate (CIS priority); a normal 2.52 Kbps rate; an enhanced PEACE priority rate of 3.54 Kbps; and three burst mode rates, with a maximum of 15.98 Kbps. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article PEACE: a Plasma Electron and Current Experiment, by A. D. Johnstone et al., from which this information was obtained.

The dual-sensor spectrometer RAPID (Research with Adaptive Particle Imaging Detectors) analyzes suprathermal plasma distributions in the energy range from 20-400 KeV for electrons and from 2 KeV/nucleon to 1.50 MeV/nucleon for ions. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article RAPID: The Imaging Energetic Particle Spectrometer on Cluster, by B. Wilken et al., from which this information was obtained.

The Spatio-Temporal Analysis of Magnetic Field Fluctuations (STAFF) experiment provides magnetic field power spectral density values parallel and perpendicular to the magnetic field and the electric field power spectral density values for several frequency ranges. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article The STAFF (Spatio-Temporal Analysis of Field Fluctuations) Experiment for the Cluster Mission, by N. Cornilleau-Wehrlin et al., from which this information was obtained.

This dataset contains 30 s duration survey spectrogram plots from the WBD instrument on the Cluster spacecraft. The spectrograms are created by 1024 point FFTs and plotted with frequency on the vertical axis, increasing time on the horizontal, and color indicating power spectral density, in relative dB. The AC electric field data are obtained by using one of the two 88m spin plane electric field antennas of the EFW instrument as a sensor. The AC magnetic field data are obtained by using one of the two search coil magnetometers (one in the spin plane, the other along the spin axis) of the STAFF instrument as a sensor.
The WBD data are obtained in one of three filter bandwidth modes: (1) 9.5 kHz, (2) 19 kHz, or (3) 77 kHz. The minimum frequency of each of these three frequency bands can be shifted up (converted) from the default 0 kHz base frequency by 125.454, 250.908 or 501.816 kHz. The time resolution of the data shown in the plots is determined from the WBD instrument mode. The highest time resolution data are sampled at 4.6 microseconds in the time domain, 4.7 milliseconds in the frequency domain (generally the 77 kHz bandwidth mode). The lowest time resolution data are sampled at 36.5 microseconds in the time domain, 37.3 milliseconds in the frequency domain (generally the 9.5 kHz bandwidth mode).
Above the spectrogram plot are a line plot panel, followed by four status lines. The line plot panel at the top provides the gain state (0 to 75 dB, in 5 dB steps) of the instrument. The four status lines provide the following information according to the color code in the upper right corner:
Data mode - whether from DSN mode (real time telemetry), or from BM2 mode (recorded onboard in Burst Mode 2) as digitally filtered or duty cycled.
Antenna - the electric field (Ey or Ez) or the magnetic field (Bx or By) antenna used.
Resolution - the data digitization level, which can be 1 bit, 4 bit or 8 bit.
Translation - the translation from base frequency of 0 kHz.
In the lower right-hand corner are the ephemeris values applicable to the start time of the plot. At the middle right-hand side are given the date and start time of the plot as well as the spacecraft number.
The University of Iowa repository maintains two types of high time resolution spectrogram plots in GIF format: a ten minute (PT10M Display Cadence) and a 30 second time span (PT30S Display Cadence). Both types of files provide information on WBD gain and operational mode, the spectral data from one spacecraft, the start date and time and ephemeris data. Overview spectrograms are also available.
The availability of these files depends on times of DSN and Pansak Ves ground station telemetry downlinks. A list of the status of the WBD instrument on each spacecraft, the telemetry time spans, operating modes and other details are available under Science Data Availability on the University of Iowa Cluster WBD web site at http://www-pw.physics.uiowa.edu/cluster/ and through the documentation section of the Cluster Active Archive (http://caa.estec.esa.int/caa).
Details on Cluster WBD Interpretation Issues can be found at http://www-pw.physics.uiowa.edu/cluster/interpretation_issues/interpretation.html
For further details on the Cluster WBD data products see Pickett, J.S., et al., "Cluster Wideband Data Products in the Cluster Active Archive" in _The Cluster Active Archive_, 2010, Springer-Verlag, pp 169-183.

The following description applies to the Wideband Data (WBD) Plasma
Wave Receivers on all four Cluster satellites, each satellite being uniquely identified
by its number (1 through 4) or its given name (Rumba, Salsa, Samba, Tango,
respectively). High time resolution calibrated waveform data sampled in one
of 3 frequency bands in the range 0-577 kHz along one axis using either an
electric field antenna or a magnetic search coil sensor. The dataset also
includes instrument mode, data quality and the angles required to orient the
measurement with respect to the magnetic field and to the GSE coordinate
system. The AC electric field data are obtained by using one of the two 88m
spin plane electric field antennas of the EFW (Electric Fields and Waves)
instrument as a sensor. The AC magnetic field data are obtained by using
one of the two search coil magnetometers (one in the spin plane, the other
along the spin axis) of the STAFF (Spatio-Temporal Analysis of Field
Fluctuations) instrument as a sensor. The WBD data are obtained in one of
three filter bandwidth modes: (1) 9.5 kHz, (2) 19 kHz, or (3) 77 kHz. The
minimum frequency of each of these three frequency bands can be shifted
up (converted) from the default 0 kHz base frequency by 125.454, 250.908
or 501.816 kHz. The time resolution of the data shown in the plots is
determined from the WBD instrument mode. The highest time resolution
data (generally the 77 kHz bandwidth mode) are sampled at 4.6
microseconds in the time domain (~4.7 milliseconds in the frequency
domain using a standard 1024 point FFT). The lowest time resolution data
(generally the 9.5 kHz bandwidth mode) are sampled at 36.5 microseconds
in the time domain (~37.3 milliseconds in the frequency domain using a
standard 1024 point FFT). The availability of these files depends on times of
DSN and Panska Ves ground station telemetry downlinks. A list of the status
of the WBD instrument on each spacecraft, the telemetry time spans,
operating modes and other details are available under Science Data
Availability on the University of Iowa Cluster WBD web site at http://www-
pw.physics.uiowa.edu/cluster/ and through the documentation section of
the Cluster Active Archive (CAA) (http://caa.estec.esa.int/caa). Details on
Cluster WBD Interpretation Issues and Caveats can be found at http://www-
pw.physics.uiowa.edu/cluster/ by clicking on the links next to the Caution symbol
in the listing on the left side of the web site. These documents are also available
from the Documentation section of the CAA website. For further details on
the Cluster WBD data products see Pickett, J.S., et al., "Cluster Wideband
Data Products in the Cluster Active Archive" in _The Cluster Active Archive_,
2010, Springer-Verlag, pp 169-183, and the Cluster WBD User Guide
archived at the CAA website in the Documentation section. ...
CALIBRATION: ... The procedure used in computing the calibrated Electric
Field and Magnetic Field values found in this file can be obtained from the
Cluster WBD Calibration Report archived at the CAA website in the
Documentation section. Because the calibration was applied in the time
domain using simple equations the raw counts actually measured by the
WBD instrument can be obtained by using these equations and solving for
'Raw Counts', keeping in mind that this number is an Integer ranging from 0
to 255. Since DC offset is a real number, the resultant when solving for raw
counts will need to be converted to the nearest whole number. A sample
IDL routine for reverse calibrating to obtain 'Raw Counts' is provided in the
WBD Calibration Report archived at the CAA. ...
CONVERSION TO FREQUENCY DOMAIN: ... In order to convert the WBD data to the frequency
domain via an FFT, the following steps need to be carried out: 1) If Electric
Field, first divide calibrated data values by 1000 to get V/m; 2) Apply
window of preference, if any (such as Hann, etc.); 3) Divide data values by
sqrt(2) to get back to the rms domain; 4) perform FFT (see Bandwidth
variable notes for non-continuous modes and/or the WBD User Guide
archived at the CAA); 5) divide by the noise bandwidth, which is equal to
the sampling frequency divided by the FFT size (see table below for
appropriate sampling frequency); 6) multiply by the appropriate constant
for the window used, if any. These steps are more fully explained in the
WBD Calibration Report archived at the CAA....
+--------------------------+
| Bandwidth | Sample Rate |
|-----------|--------------|
| 9.5 kHz | 27.443 kHz |
| 19 kHz | 54.886 kHz |
| 77 kHz | 219.544 kHz |
+--------------------------+
COORDINATE SYSTEM USED: ... One axis measurements made in the
Antenna Coordinate System, i.e., if electric field measurement, it will either
be Ey or Ez, both of which are in the spin plane of the spacecraft, and if
magnetic field measurement, it will either be Bx, along the spin axis, or By,
in spin plane. The user of WBD data should refer to the WBD User Guide,
archived at the CAA, Section 5.4.1 and Figure 5.3 for a description of the
three orientation angles provided in these files. Since WBD measurements
are made along one axis only, these three angles provide the only means for
orienting the WBD measurements with respect to a geocentric coordinate
system and to the magnetic field direction ...

The Waves of HIgh frequency and Sounder for Probing of Electron density
by Relaxation (WHISPER) performs the measurement of the electron density
on the four satellites of the Cluster project. The two main purposes of
the WHISPER experiment are to record the natural waves and to make a
diagnostic of the electron density using the sounding technique.
The various working modes and the fourier transforms calculated on board
provide a good frequency resolution obtained in the bandwidth 2-83 kHz.
Onboard data compression by the Digital Wave Processing (DWP) intrument
allows a good dynamic and level resolution of the electric signal amplitude.

The Waves of HIgh frequency and Sounder for Probing of Electron density
by Relaxation (WHISPER) performs the measurement of the electron density
on the four satellites of the Cluster project. The two main purposes of
the WHISPER experiment are to record the natural waves and to make a
diagnostic of the electron density using the sounding technique.
The various working modes and the fourier transforms calculated on board
provide a good frequency resolution obtained in the bandwidth 2-83 kHz.
Onboard data compression by the Digital Wave Processing (DWP) intrument
allows a good dynamic and level resolution of the electric signal amplitude.

The Waves of HF and Sounder for Probing Electron Density by Relaxation (WHISPER) experiment provides measurements of the electron density via active sounding of plasma resonances and records via passive wave analysis the natural wave emissions in the high-frequency range, from 4-80 KHz. For more details of the Cluster mission, the spacecraft, and its instruments, see the report Cluster: mission, payload and supporting activities, March 1993, ESA SP-1159, and the included article WHISPER, a Sounder and High-Frequency Wave Analyser Experiment, by P. M. E. Decreau et al., from which this information was obtained.